Glycosidase inhibition by cyclic sulfonium compounds

Inhibitory activities of various cyclic sulfonium compounds including salacinol against several glycosidases were studied and some compounds showed significant inhibition. The sulfonium ion structure was found to be essential for the inhibitory activity. Specific inhibition of salacinol toward rice alpha-glucosidase was ascribed to the tether arm.     

4-Methyl-5-phenyl triazoles as selective inhibitors of 11beta-hydroxysteroid dehydrogenase type I

4-Methyl-5-phenyl-(1,2,4)-triazoles were identified as selective inhibitors of 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1). They were active in vitro and in an in vivo mouse pharmacodynamic (PD) model. The synthesis and structure activity relationships are presented.     

Glycosidase inhibition by plant alkaloids which are structural analogues of monosaccharides

]The inhibitory activities of three plant alkaloids, deoxynojirimycin, 2,5-dihydroxymethyl-3,4-dihydroxypyrrolidine and 1,5 dideoxy-1,5-imino-D-mannitol towards glycosidases from several sources have been compared. These are structural analogues of D-glucose, D-fructose and D-mannose respectively. The occurrence of 2,5-dihydroxymethyl-3,4-dihydroxypyrrolidine in Lonchocarpus sericeus seed is confirmed and has been shown to be responsible for the glucosidase inhibition wrongly attributed to 1,5-dideoxy-1,5-imino-D-mannitol in a previous report.     

The Synthesis of some 1-glycosyl-6-nitroindoles

Condensation of 6-nitroindoline with 5-O-trityl-L-arabinose, -D-fucose, -D-arabinose, or -L-rhamnose gave the corresponding 1-glycosyl-6-nitroindolines, from which, after acetylation, dehydrogenation, and removal of protecting groups, 1-α-and -β-L-arabinofuranosyl, 1-β-D-fucopyranosyl, 1-α-D-arabinopyranosyl, and 1-α-and -β-L-rhamnopyranosyl derivatives of 6-nitroindole were obtained. The configuration of the arabinose and fucose derivatives was established by p.m.r. spectroscopy. Comparison of the p.m.r. and c.d. spectra of the products obtained from the glycosyl-nitroindoles by application in sequence of periodate oxidation, borohydride reduction, and acetylation allowed assignment of the configuration of the rhamnose derivatives.     

Synthesis and biological evaluation of novel triazoles and isoxazoles linked 2-phenyl benzothiazole as potential anticancer agents

A new series of isoxazoles and triazoles linked 2-phenyl benzothiazole were synthesized and evaluated for their anticancer activity. These compounds have been tested for their cytotoxicity three cancer cell lines. Among the compounds tested, compound 5d showed good cytotoxicity against Colo-205 and A549 cells in comparison to standard control PMX 610(1). Further compound 5d has been tested for its apoptotic activity and its inhibitory activity against caspase and PARP proteins. Hence this compound has the potential that it can be selected for further biological studies.     

1-[4-(1H-Benzoimidazol-2-yl)-phenyl]-3-[4-(1H-benzoimidazol-2-yl)-phenyl]-urea derivatives as small molecule heparanase inhibitors

A novel class of 1-[4-(1H-benzoimidazol-2-yl)-phenyl]-3-[4-(1H-benzoimidazol-2-yl)-phenyl]-ureas are described as potent inhibitors of heparanase. Among them are 1,3-bis-[4-(1H-benzoimidazol-2-yl)-phenyl]-urea (7a) and 1,3-bis-[4-(5,6-dimethyl-1H-benzoimidazol-2-yl)-phenyl]-urea (7d), which displayed good heparanase inhibitory activity (IC(50) 0.075-0.27 microM). Compound 7a showed good efficacy in a B16 metastasis model.     

Conversion of 4-hydroxyacetophenone into 4-phenyl acetate by a flavin adenine dinucleotide-containing Baeyer-Villiger-type monooxygenase

An arylketone monooxygenase was purified from Pseudomonas putida JD1 by ion exchange and affinity chromatography. It had the characteristics of a Baeyer-Villiger-type monooxygenase and converted its substrate, 4-hydroxyacetophenone, into 4-hydroxyphenyl acetate with the consumption of one molecule of oxygen and oxidation of one molecule of NADPH per molecule of substrate. The enzyme was a monomer with an M(r) of about 70,000 and contained one molecule of flavin adenine dinucleotide (FAD). The enzyme was specific for NADPH as the electron donor, and spectral studies showed rapid reduction of the FAD by NADPH but not by NADH. Other arylketones were substrates, including acetophenone and 4-hydroxypropiophenone, which were converted into phenyl acetate and 4-hydroxyphenyl propionate, respectively. The enzyme displayed Michaelis-Menten kinetics with apparent K(m) values of 47 microM for 4-hydroxyacetophenone, 384 microM for acetophenone, and 23 microM for 4-hydroxypropiophenone. The apparent K(m) value for NADPH with 4-hydroxyacetophenone as substrate was 17.5 microM. The N-terminal sequence did not show any similarity to other proteins, but an internal sequence was very similar to part of the proposed NADPH binding site in the Baeyer-Villiger monooxygenase cyclohexanone monooxygenase from an Acinetobacter sp.     

Noncytotoxic inhibition of viral infection through eIF4F-independent suppression of translation by 4EGi-1

The eukaryotic initiation factor eIF4F recruits ribosomes to capped mRNAs while eIF2 mediates start codon recognition to initiate protein synthesis. Increasing interest in targeting translation to suppress tumor growth has led to the development of new classes of inhibitors, including 4EGi-1, which disrupts eIF4F complexes. However, the full effects of this inhibitor and its potential uses in the treatment of other disease states remain unclear. Here, we show that overall rates of protein synthesis in primary human cells were affected only modestly by eIF4F disruption using the mTOR inhibitor Torin1, yet were highly sensitive to 4EGi-1. Translational suppression occurred even at concentrations of 4EGi-1 that were below those required to significantly alter eIF4F levels but were instead found to increase the association of ribosomal complexes containing inactive eIF2α. Although highly stable in culture, the effects of 4EGi-1 on both cellular protein synthesis and ribosome association were readily reversible upon inhibitor removal. In addition, despite potently inhibiting translation, prolonged exposure to 4EGi-1 had only modest effects on cell morphology and protein abundance without affecting viability or stress tolerance to any significant degree, although differential effects on heat shock protein (hsp) expression highlighted distinct 4EGi-1-sensitive modes of hsp induction. In contrast, 4EGi-1 potently suppressed poxvirus replication as well as both reactivation and lytic phases of herpesvirus infection. These findings identify a novel way in which 4EGi-1 affects the host cell's protein synthesis machinery and demonstrate its potential as a noncytotoxic inhibitor of diverse forms of viral infection.     

Synthesis and potent antimicrobial activity of some novel 2-phenyl or methyl-4H-1-benzopyran-4-ones carrying amidinobenzimidazoles

Series of flavones and methyl-4H-1-benzopyran-4-ones carrying mono or diamidinobenzimidazoles at different positions were synthesized and evaluated for antibacterial and antifungal activities against E. coli, S. aureus, MRSA (methicillin-resistant S. aureus), MRSE (methicillin-resistant S. epidermidis), S. faecalis and C. albicans, C. krusei. The results showed that while all diamidines are inactive, the compounds having monoamidinobenzimidazoles at the C-6 position of the 2-phenyl-4H-1-benzopyran-4-one have potent antibacterial activities, particularly, against Gram-positive bacteria. Compounds 23 and 22 exhibited the best inhibitory activity with MIC values of 1.56 microg/ml against S. aureus, MRSA, MRSE and 3.12 microg/ml against C. albicans, respectively.     

Acetylcholinesterase inhibition by two phosphoric 4-nitroanilides

Two phosphoric 4-nitroanilides Z2P(O)NH-phi-NO2 (A, Z = Me; B, Z = NMe2) have been prepared and purified by chromatographic techniques. Their spectral data (uv, ir and 1H-nmr) have been determined, and compared with those of other similar compounds. Their ability to inhibit acetylcholinesterase has been measured by a modification of Ellman's method. The data, as computed according to the Michaelis scheme, indicate that A is not an inhibitor, whereas B is a reversible mixed one. These differences are discussed in terms of hydrophobic interactions.     

Myosin surface loop 4 modulates inhibition of actomyosin 1b ATPase activity by tropomyosin

Structural studies of the class I myosin, MyoE, led to the predictions that loop 4, a surface loop near the actin-binding region that is longer in class I myosins than in other myosin subclasses, might limit binding of myosins I to actin when actin-binding proteins, like tropomyosin, are present, and might account for the exclusion of myosin I from stress fibers. To test these hypotheses, mutant molecules of the related mammalian class I myosin, Myo1b, in which loop 4 was truncated (from an amino acid sequence of RMNGLDES to NGLD) or replaced with the shorter and distinct loop 4 found in Dictyostelium myosin II (GAGEGA), were expressed in vitro and their interaction with actin and with actin-tropomyosin was tested. Saturating amounts of expressed fibroblast tropomyosin-2 resulted in a decrease in the maximum actin-activated Mg2+-ATPase activity of wild-type Myo1b but had little or no effect on the actin-activated Mg2+-ATPase activity of the two mutants. In motility assays, few actin filaments bound tightly to Myo1b-WT-coated cover slips when tropomyosin-2 was present, whereas actin filaments both bound and were translocated by Myo1b-NGLD or Myo1b-GAGEGA in both the presence and absence of tropomyosin-2. When expressed in mammalian cells, like the wild type, the mutant myosins were largely excluded from tropomyosin-containing actin filaments, indicating that in the cell additional factors besides loop 4 determine targeting of myosins I to specific subpopulations of actin filaments.     

KIR3DL1 polymorphisms that affect NK cell inhibition by HLA-Bw4 ligand

The killer cell Ig-like receptor (KIR) gene family encodes MHC class I receptors expressed by NK cells and several T cell subpopulations. Factors contributing to human KIR haplotype diversity are differences in gene number, gene content, and allelic polymorphism. Whereas functional and clinical consequences of the first two factors are established, knowledge of the effects of KIR gene polymorphism is limited to special cases in which signaling function is reversed or cell surface expression lost. In this study we use retrovirally transduced human cell lines to show that 3DL1*002 is a stronger inhibitory receptor for HLA-Bw4 ligands than 3DL1*007. Analysis of mutant 3DL1*002 and 3DL1*007 molecules demonstrates that residue 238 in the D2 domain and 320 in the transmembrane region contribute to the difference in receptor strength. Neither position 238 nor 320 is predicted to interact directly with HLA-Bw4 ligand. This study also revealed that KIR3DL1 and LILRB1 both contribute to developing an inhibitory response to HLA-Bw4 ligands.     

Aromatase inhibition by 4-thiosubstituted-4-androstene-3,17-dione derivatives

The synthesis and evaluation of 4-thiosubstituted-4-androstenedione analogs as inhibitors of estrogen synthetase (aromatase) is described. All compounds were prepared by the addition of various thiol reagents to 4 beta,5 beta-epoxyandrostanedione. Inhibitory activity of synthesized compounds was assessed using a human placental microsomal preparation as the enzyme source and [1 beta-3H]4-androstene-3,17-dione as substrate. Synthesized compounds exhibiting high inhibitory activity were further evaluated under initial velocity conditions to determine apparent Ki values. Several compounds were effective competitive inhibitors, and have apparent Ki values ranging from 34 to 52 nM, with the apparent Km for androstenedione being 54 nM. The results of these studies demonstrate a tightly fitted enzyme pocket that can accommodate bulky substituents at the C-4 position of androstenedione not to exceed 4.3 A in width and 5.5 A in length.     

Adamantyl triazoles as selective inhibitors of 11beta-hydroxysteroid dehydrogenase type 1

Adamantyl triazoles were identified as selective inhibitors of 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1). They are active both in in vitro and in in vivo pharmacodynamic models. The synthesis and structure-activity relationships of these inhibitors are presented.     

Processing glucosidase inhibition by 1-azafagomine

Natural azasugars have the ring oxygen substituted by nitrogen. They show potent inhibitory activity against glycosidases. The effect of substituting the ring carbon with nitrogen was examined with 1-azafagomine. 1-Azafagomine exhibited similar activity against processing glucosidase to that of fagomine.     

Heterocyclic derivatives of sugars: the formation of 1-glycosyl-3-methylpyrazol-5-ones from hydrazones

Conditions to effect the conversion of monosaccharide and disaccharide hydrazones to 1-glycosyl-3-methylpyrazol-5-ones were examined. The sugar pyrazolone derivatives were sensitive to oxidation, but high yields were achieved with 2,2,2-trifluoroethyl acetoacetate in mildly acidic solution. Azo coupling of the pyrazolones produced highly coloured azopyrazolone derivatives that prevented further degradation, and these may prove useful labels for chromatographic analysis of carbohydrates.     

Glycosidase activity profiling for bacterial identification by a chemical proteomics approach

Genome sequencing projects are suggesting there are dozens of glycosidase sequences that could be used to fingerprint cell types and serve as starting points for biocatalyst discovery. Herein, we present a simple chemical proteomics approach to profile intracellular glycosidase activities of three different bacterial cell extracts using a synthetic α- and β-linked library of 18 representative substrates with electrospray ionization-mass spectrometry (ESI-MS) reaction monitoring. Three target bacteria – Escherichia coli K12, Bacillus cereus and Pseudomonas aeruginosa – can be easily differentiated by this method. Compared with traditional chromogenic and fluorogenic methods to profile bacterial enzyme activities individually, this MS-based method can detect multiple enzyme activities in one reaction and easily highlight activity differences between whole cell extracts.     

Bis-aryl triazoles as selective inhibitors of 11beta-hydroxysteroid dehydrogenase type 1

3-Aryl-5-phenyl-(1,2,4)-triazoles were identified as selective inhibitors of 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1). They are active in both in vitro and an in vivo mouse pharmacodynamic (PD) model. The synthesis and structure activity relationships are presented.     

GPIHBP1 stabilizes lipoprotein lipase and prevents its inhibition by angiopoietin-like 3 and angiopoietin-like 4

Glycosylphosphatidylinositol-anchored HDL-binding protein (GPIHBP1) binds both LPL and chylomicrons, suggesting that GPIHBP1 is a platform for LPL-dependent processing of triglyceride (TG)-rich lipoproteins. Here, we investigated whether GPIHBP1 affects LPL activity in the absence and presence of LPL inhibitors angiopoietin-like (ANGPTL)3 and ANGPTL4. Like heparin, GPIHBP1 stabilized but did not activate LPL. ANGPTL4 potently inhibited nonstabilized LPL as well as heparin-stabilized LPL but not GPIHBP1-stabilized LPL. Like ANGPTL4, ANGPTL3 inhibited nonstabilized LPL but not GPIHBP1-stabilized LPL. ANGPTL3 also inhibited heparin-stabilized LPL but with less potency than nonstabilized LPL. Consistent with these in vitro findings, fasting serum TGs of Angptl4^−/−/Gpihbp1^−/− mice were lower than those of Gpihbp1^−/− mice and approached those of wild-type littermates. In contrast, serum TGs of Angptl3^−/−/Gpihbp1^−/− mice were only slightly lower than those of Gpihbp1^−/− mice. Treating Gpihbp1^−/− mice with ANGPTL4- or ANGPTL3-neutralizing antibodies recapitulated the double knockout phenotypes. These data suggest that GPIHBP1 functions as an LPL stabilizer. Moreover, therapeutic agents that prevent LPL inhibition by ANGPTL4 or, to a lesser extent, ANGPTL3, may benefit individuals with hyperlipidemia caused by gene mutations associated with decreased LPL stability.     

Glycosidase inhibitors of gem-diamine 1-N-iminosugars. structures in media of enzyme assays

The relationships between structures and inhibitory activities of glycosidase inhibitors of gem-diamine 1-N-iminosugars in media of enzyme assays have been investigated. It has been proved that gem-diamine 1-N-iminosugar smoothly undergoes a structural change to a hydrated ketone or its derivative via a hemiaminal in the media (pH 5.0-6.3), and that the products generated in the media as well as the parent gem-diamine 1-N-iminosugars potently inhibit glycosidases.